2,225 research outputs found
Negative to Positive Magnetoresistance transition in Functionalization of Carbon nanotube and Polyaniline Composite
Electrical resistivity and magnetoresistance(MR) in polyaniline(PANI) with
carbon nanotube(CNT) and functionalized carbon nanotube(fCNT) composites have
been studied for different weight percentage down to the temperature 4.2K and
up to magnetic field 5T. Resistivity increases significantly in composite at
low temperature due to functionalization of CNT compare to only CNT.
Interestingly transition from negative to positive magnetoresistance has been
observed for 10wt% of composite as the effect of disorder is more in fCNT/PANI.
This result depicts that the MR has strong dependency on disorder in the
composite system. The transition of MR has been explained in the basis of
polaron-bipolaron model. The long range Coulomb interaction between two
polarons screened by disorder in the composite of fCNT/PANI, increases the
effective on-site Coulomb repulsion energy to form bipolaron which leads to
change the sign of MR from negative to positive.Comment: 5 pages, 8 figures; typos adde
Macro-Financial Parameters Influencing Bitcoin Prices: Evidence from Symmetric and Asymmetric ARDL Models
Bitcoins are evolving as a modern class of investment assets and it is crucial for investors to manage their investment risk. This paper examines the impact of macroeconomic-financial indicators on Bitcoin price using symmetric and asymmetric version of autoregressive distributed lag (ARDL) models with structural breaks. The asymmetric long-run association ascertained between Bitcoin prices and the macroeconomic-financial indicators is evident. Our empirical results indicate that the Bitcoin cannot be used to hedge against the inflation, Federal funds rate, stock markets and commodity markets. We further find that Bitcoin can be regarded as a hedging device for the oil prices. Our findings have significant implications for market participants who consider including alternate investment assets in their portfolios
Tuning spin one channel to exotic orbital two-channel Kondo effect in ferrimagnetic composites of LaNiO3 and CoFe2O4
We report the tuning from spin one channel (1CK) to orbital two-channel Kondo
(2CK) effect by varying CoFe2O4 (CFO) content in the composites with LaNiO3
(LNO) along with the presence of ferrimagnetism. Although there is no signature
of resistivity upturn in case of pure LNO, all the composites exhibit a
distinct upturn in the temperature range 30-80 K. For composite with lower
percentage of CFO (10 %), the electron spin plays the key role in the emergence
of resistivity upturn which is affected by external magnetic field. On the
other hand, when the CFO content is increased (15%), the upturn shows strong
robustness against high magnetic field (14 T) and a crossover in temperature
variation from lnT to T^1/2 at the Kondo temperature, indicating the appearance
of orbital 2CK effect. The orbital 2CK effect is originated due to the
scattering of conduction electrons from the structural two-level systems which
is created at the interfaces between the two phases (LNO and CFO) of different
crystal structures as well as inside the crystal planes. A negative
magnetoresistance (MR) is observed at low temperature (< 30 K) for composites
containing both lower (10 %) and higher percentage (15 %) of CFO. We have
analyzed the negative MR using Khosla and Fisher semi-empirical model based on
spin dependent scattering of conduction electrons from localized spins.Comment: 14 pages including supplementary materials and 12 figure
Reconfigurable Multifunctional van der Waals Ferroelectric Devices and Logic Circuits
In this work, we demonstrate the suitability of Reconfigurable Ferroelectric
Field-Effect- Transistors (Re-FeFET) for designing non-volatile reconfigurable
logic-in-memory circuits with multifunctional capabilities. Modulation of the
energy landscape within a homojunction of a 2D tungsten diselenide (WSe)
layer is achieved by independently controlling two split-gate electrodes made
of a ferroelectric 2D copper indium thiophosphate (CuInPS) layer.
Controlling the state encoded in the Program Gate enables switching between p,
n and ambipolar FeFET operating modes. The transistors exhibit on-off ratios
exceeding 10 and hysteresis windows of up to 10 V width. The homojunction
can change from ohmic-like to diode behavior, with a large rectification ratio
of 10. When programmed in the diode mode, the large built-in p-n junction
electric field enables efficient separation of photogenerated carriers, making
the device attractive for energy harvesting applications. The implementation of
the Re-FeFET for reconfigurable logic functions shows how a circuit can be
reconfigured to emulate either polymorphic ferroelectric NAND/AND
logic-in-memory or electronic XNOR logic with long retention time exceeding
10 seconds. We also illustrate how a circuit design made of just two
Re-FeFETs exhibits high logic expressivity with reconfigurability at runtime to
implement several key non-volatile 2-input logic functions. Moreover, the
Re-FeFET circuit demonstrates remarkable compactness, with an up to 80%
reduction in transistor count compared to standard CMOS design. The 2D van de
Waals Re-FeFET devices therefore exhibit groundbreaking potential for both
More-than-Moore and beyond-Moore future of electronics, in particular for an
energy-efficient implementation of in-memory computing and machine learning
hardware, due to their multifunctionality and design compactness.Comment: 23 pages, 5 figures; Supporting Information: 12 pages, 6 figure
Proximitized spin-phonon coupling in topological insulator due to two-dimensional antiferromagnet
Induced magnetic order in a topological insulator (TI) can be realized either
by depositing magnetic adatoms on the surface of a TI or engineering the
interface with epitaxial thin film or stacked assembly of two-dimensional (2D)
van der Waals (vdW) materials. Herein, we report the observation of spin-phonon
coupling in the otherwise non-magnetic TI BiTe, due
to the proximity of FePS (an antiferromagnet (AFM),
120 K), in a vdW heterostructure framework. Temperature-dependent Raman
spectroscopic studies reveal deviation from the usual phonon anharmonicity
at/below 60 K in the peak position (self-energy) and linewidth (lifetime) of
the characteristic phonon modes of BiTe (106 cm and 138
cm) in the stacked heterostructure. The Ginzburg-Landau (GL) formalism,
where the respective phonon frequencies of BiTe couple to phonons
of similar frequencies of FePS in the AFM phase, has been adopted to
understand the origin of the hybrid magneto-elastic modes. At the same time,
the reduction of characteristic of FePS from 120 K in
isolated flakes to 65 K in the heterostructure, possibly due to the interfacial
strain, which leads to smaller Fe-S-Fe bond angles as corroborated by
computational studies using density functional theory (DFT). Besides, our data
suggest a double softening of phonon modes of BiTe
(at 30 K and 60 K), which in turn, demonstrates Raman scattering as a possible
probe for delineating the magnetic ordering in bulk and surface of a hybrid
topological insulator
Increased dynamics in the 40-57 Ω-loop of the G41S variant of human cytochrome c promote its pro-apoptotic conformation
Thrombocytopenia 4 is an inherited autosomal dominant thrombocytopenia, which occurs due to mutations in the human gene for cytochrome c that results in enhanced mitochondrial apoptotic activity. The Gly41Ser mutation was the first to be reported. Here we report stopped-flow kinetic studies of azide binding to human ferricytochrome c and its Gly41Ser variant, together with backbone amide H/D exchange and 15N-relaxation dynamics using NMR spectroscopy, to show that alternative conformations are kinetically and thermodynamically more readily accessible for the Gly41Ser variant than for the wild-type protein. Our work reveals a direct conformational link between the 40-57 Ω-loop in which residue 41 resides and the dynamical properties of the axial ligand to the heme iron, Met80, such that the replacement of glycine by serine promotes the dissociation of the Met80 ligand, thereby increasing the population of a peroxidase active state, which is a key non-native conformational state in apoptosis
Metabolism within the tumor microenvironment and its implication on cancer progression: an ongoing therapeutic target
Since reprogramming energy metabolism is considered a new hallmark of cancer, tumor metabolism is again in the spotlight of cancer research. Many studies have been carried out and many possible therapies have been developed in the last years. However, tumor cells are not alone. A series of extracellular components and stromal cells, such as endothelial cells, cancer-associated fibroblasts, tumor-associated macrophages and tumor-infiltrating T cells, surround tumor cells in the so-called tumor microenvironment. Metabolic features of these cells are being studied in deep in order to find relationships between metabolism within the tumor microenvironment and tumor progression. Moreover, it cannot be forgotten that tumor growth is able to modulate host metabolism and homeostasis, so that tumor microenvironment is not the whole story. Importantly, the metabolic switch in cancer is just a consequence of the flexibility and adaptability of metabolism and should not be surprising. Treatments of cancer patients with combined therapies including anti-tumor agents with those targeting stromal cell metabolism, anti-angiogenic drugs and/or immunotherapy are being developed as promising therapeutics.Mª Carmen Ocaña is recipient of a predoctoral FPU grant from the Spanish Ministry of Education, Culture and Sport. Supported by grants BIO2014-56092-R (MINECO and FEDER), P12-CTS-1507 (Andalusian Government and FEDER) and funds from group BIO-267 (Andalusian Government). The "CIBER de Enfermedades Raras" is an initiative from the ISCIII (Spain). The funders had no role in the study design, data collection and analysis, decision to publish or preparation of the manuscript
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